The placenta is a fetomaternal organ that functions to transport nutrients and gases to the fetus and facilitates waste elimination through the umbilical cord and maternal blood supply. The placenta also has endocrine and metabolic functions needed during pregnancy. The placenta comprises both maternal and embryo-derived tissue including the umbilical cord, the amniotic membrane that surrounds the fetus, and the outer chorionic membrane. The amniotic membrane is avascular and comprises an epithelial layer and an inner stromal layer.
The amniotic membrane is a rich source of stem cells, growth factors, antioxidants, compounds having antimicrobial properties, and various organic compounds that support fetal growth. The amniotic membrane is immune-privileged and does not illicit an immune response by the mother despite its fetal origin. The amniotic membrane's stem cells have the capacity to differentiate into many types of tissue and have been the subject of extensive research for their therapeutic uses.